Overhyped or not, the cloud has deeply changed how we build and run software—and not just because IaaSes make VMs trivial to spin up and PaaSes make environments easy to set up. As a user you know what’s changed, and you understand the concept “as a service” (well, ever since you started running *nix); and, thank goodness, you don’t really have to worry about the physical details that make those services run.